Evangelical pastor Rick Warren has declared his support for California’s Proposition 8.

Proposition 8 seeks to amend California’s state constitution to define marriage as between only one man and one woman, invalidating last spring’s Supreme Court of California decision that legalized same-sex “marriages.”

Warren, the pastor of California’s Saddleback mega-church and author of the 2002 devotional bestseller “The Purpose-Driven Life,”  endorsed Proposition 8 in an Oct. 23 e-mail to members of his church, Baptist Press reported Oct. 27.

Warren strongly denounced efforts to redefine marriage.

“For 5,000 years, EVERY culture and EVERY religion — not just Christianity — has defined marriage as a contract between men and women,” Warren wrote. “There is no reason to change the universal, historical definition of marriage to appease 2% of our population. This is one issue that both Democrats and Republicans can agree on. Both Barack Obama and John McCain have publicly opposed the redefinition of marriage to include so-called ‘gay marriage.’ Even some gay leaders, like Al Rantel of KABC oppose watering down the definition of marriage.”

Added Warren, “This is not a political issue, it is a moral issue that God has spoken clearly about. There is no doubt where we should stand on this issue.”

Warren concluded his email by reminding his flock how important it is to vote in favor of Proposition 8. 

“This will be a close contest, maybe even decided by a few thousand votes,” he said. “I urge you to VOTE YES on Proposition 8 — to preserve the biblical definition of marriage. Don’t forget to vote!”

Warren’s Proposition 8 endorsement comes as a blow to political liberals who had hoped the prominent Evangelical pastor’s reputation as a theological moderate might lead him to mute his opposition to “same-sex” marriage.

It’s not the first time during the campaign Warren has caused problems for that political constituency. When Barack Obama participated along with John McCain in Warren’s Aug. 16 Saddleback Civil Forum, Warren asked the Democratic presidential candidate an abortion-related question about when a baby acquires human rights.

Obama’s peculiar reply — that “answering that question with specificity, you know, is above my pay grade” — is widely regarded as one of the worst gaffes he’s made on the presidential campaign trail.

— Tom McFeely